
52 Wireless Networks Resources Trading for QoS Performance
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0
0.5
1
1.5
2
2.5
x 10
4
the frequency access ratio of femtocells
green factor(b/J)
N
f
=10
N
f
=30
N
f
=50
N
f
=70
N
f
=90
N
f
=110
Figure 2.16: Green factor versus frequency access ratio of femtocells (η =0.1).
1. When N
f
is less than 30, the green factor increases when r
f
increases.
When N
f
is larger than 50, the green factor first increases, and then
decreases when r
f
increases. The more femtocells, the larger spectrum
efficiency can be obtained. But, the more femtocells, the larger inter-
ference among femtocells. Thus, it is desirable to fully utilize femtocells
when N
f
is small ...